#24595: alter field type on MySQL "forgets" nullability (and more)
--------------------------------+--------------------
Reporter: simonpercivall | Owner: nobody
Type: Bug | Status: new
Component: Migrations | Version: 1.7
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Easy pickings: 0 | UI/UX: 0
--------------------------------+--------------------
A migration changing field type on MySQL will remove "NOT NULL" (and every
other attribute) from the field. This is because MODIFY COLUMN on MySQL
requires the whole field definition to be repeated, not just the type.
So for instance:
{{{
class T(models.Model):
field = models.SmallIntegerField()
}}}
will create a table:
{{{
CREATE TABLE `app_t` (
...
`field` smallint(6) NOT NULL,
...
) ENGINE=InnoDB
}}}
Changing the field definition to:
{{{
...
field = models.IntegerField()
...
}}}
will create a migration:
{{{
...
migrations.AlterField(
model_name='t',
name='field',
field=models.IntegerField(),
)
...
}}}
resulting in the SQL
{{{
ALTER TABLE `app_t` MODIFY `field` integer
}}}
resulting in the table:
{{{
CREATE TABLE `app_t` (
...
``field` int(11) DEFAULT NULL,
...
)
}}}
This applies to 1.7 through 1.8.
--
Ticket URL: <https://code.djangoproject.com/ticket/24595>
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